mm-video: vidc: add support for opaque-format gralloc-buffers in encoding

Camera3.0 queues gralloc-allocated meta-buffers in opaque color format
unlike the camera2 which pre-announces NV12 color format. These buffers
have Venus's native NV12 format and do not need a color conversion.
Introduce a flag to explicitly indicate color-conversion rather than
derive it from proxy-format, since camera3 buffers are opaque buffers
but need no color-conversion.

Change-Id: Ib1acfc60031444de83ba5d450fddf82c561328bd
3 files changed